In recent years, the structures of wires or electrodes in electronic devices such as DRAM (Dynamic Random Access Memory) have been becoming finer and more complex to achieve higher performance, and the improvement of shape accuracy for these electronic devices has been desired.
To form electrodes or wires in the electronic devices, in general, trenches are formed at positions corresponding to the electrodes or wires on the substrate, a metal material which will become the electrodes or wires is embedded into the trenches, and an excessive portion is removed by chemical mechanical polishing or the like.
Heretofore, aluminum having high conductivity has been widely used as an electrode material or wire material to be embedded into the trenches. When aluminum is used as the material, physical processes such as deposition and sputtering have been mainly used to fill the trenches (refer to JP-A 6-349833 and JP-A 11-195652). However, to embed aluminum into the trenches, according to a conventionally known embedding method, when the minimum distance of the opening on the surface of a trench is about 300 nm or less and the aspect ratio (value obtained by dividing the depth of the trench by the minimum distance of the opening on the surface of the trench) of the trench is about 3 or more, a void where aluminum is not embedded may be formed in the trench Therefore, there are limits in meeting demand for the fine and complex structures of wires and electrodes.
In addition, the above physical processes need a high vacuum apparatus and a high-output power source, thereby causing such problems that it is difficult to apply the processes to large substrates and the process cost is high.